Is there a check engine light on? Here is an idle learn procedure to try:
PI01346A: ECM Idle Learn Procedure - 3.2 crank crankshaft DTC ECM LA3 learn MIL misfire no P0341 P0336 P1336 P1374 PCM sensor stall start - (Sep 18, 2003)
Subject: ECM Idle Learn Procedure
When servicing the vehicle with the VIN you entered, the following diagnosis might be helpful if the vehicle exhibits the described symptoms.
On some 2003 and 2004 CTS vehicles, technicians may be unable to perform an idle relearn procedure as per SI document number 813266. If no other codes or driveabilty concerns exist, technicians should perform the following:
Idle Learn Procedure
The engine control learns the idle position of the throttle body for correct operation. When the throttle body or ECM is replaced, this procedure must be performed to ensure correct idle operation. The engine idle may be unstable or a DTC may set if the idle position has not been learned. Perform the following procedure in order to allow the ECM to learn the idle position:
Ensure that the following conditions are met:
" The vehicle speed is 0 mph.
" The accelerator pedal angle is less than 14.9 percent.
" The battery voltage is more than 10 volts.
" The engine coolant temperature (ECT) is between 5-60 C (41-140 F).
" The intake air temperature (IAT) is between 5-60 C (41-140 F).
Turn OFF the ignition for 30 seconds.
Turn ON the ignition, with the engine OFF for 1 minute.
Turn OFF the ignition.
Turn ON the ignition, clear codes if required.
Please follow this diagnosis process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed. If these steps do not resolve the condition, please contact GM TAC for further diagnostic assistance. This diagnostic approach was developed for the vehicle with the VIN you entered and should not be automatically be used for other vehicles with similar symptoms.
(03, 04 Cadillac CTS)
GM bulletins are intended for use by professional technicians, NOT a "do-it-yourselfer". They are written to inform these technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions, and know-how to do a job properly and safely. If a condition is described, DO NOT assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See your GM dealer for information on whether your vehicle may benefit from the information.
It may or may not correct the condition. If it has a check engine light, have the codes read, it may lead to a diagnostic process. Not knowing why the heads were replaced, I would assume that it jumped time and bent valves. It is possible that the timing was not set correctly. It is a bit of a process to set cam timing on this engine, and possibilities exist to have it off enough to create an idle problem that would not be noticed at higher rpm's. What were the condition of the heads installed? It could be possible that there is leakage with the valves that would cause misfires at idle, and not at higher rpm's as well.
Friday, May 29th, 2009 AT 9:35 PM